As the trend to conserve energy continues, more individuals are demanding and more governmental entities are mandating that houses and commercial facilities undergo periodic energy audits. An energy audit is a service where a building structure's energy efficiency is evaluated by a person using professional equipment as blower door and infra-red cameras), with the aim to suggest the best ways to improve energy efficiency in heating and cooling the structure.
An energy audit involves recording various characteristics of the building envelope including the walls, ceilings, floors, doors, windows, and skylights. For each of these components the area and resistance to heat flow (R-value) is measured or estimated. The leakage rate or infiltration of air through the building envelope is of concern and is strongly affected by window construction and quality of door seals such as weather stripping. The goal of an audit is to quantify the building's overall thermal performance. The audit may also assess the efficiency, physical condition, and programming of mechanical systems such as the heating, ventilation, air conditioning (HVAC) equipment, and thermostat.
Leaks in an air duct system often account for a large percentage of energy being wasted in a typical home. In a residence, the percentage of air that escapes out of an air duct system due to leaks, on average, is approximately twenty-five percent (25%). Given that in some areas of the country, sixty percent (60%) to seventy percent (70%) of the cost of a household's monthly utilities bill is due to the operation of the HVAC system, air leakage in an air duct system may represent a significant waste of both monetary and energy resources.
Measuring the leakage in an air duct system is generally the most time consuming portion of a home energy audit. In fact, as much as fifty percent (50%) of the time required to perform a home energy audit is consumed in testing air leakage of an air duct system. The majority of that time is spent sealing off the various air vents so that the air duct system can be pressurized or depressurized to measure the air leaks.
Current methods of sealing off the air vents involve the use of a special adhesive tape that adheres to the face of an air vent. There are, however, certain drawbacks to the use of this adhesive tape. Applying and removing the adhesive tape to all of the air vents takes a significant amount of time because the adhesive tape is cumbersome and awkward to use. Commonly, the tape sticks to itself and those pieces have to be thrown away unused. The tape is generally stored in bulky spools that are heavy and difficult to maneuver. When the tape is removed from the spools, it can generate an extremely loud noise that may wake up members of a home that are asleep during the day, such as, for example a baby or elderly person taking a nap, or be disruptive to ongoing business concerns.
Another drawback is that the tape does not provide the best seal possible for the air duct system. Even after the tape is applied to the air vent, air may still enter and leave the air duct system beneath the face of the air vent that touches the wall or ceilings surface because the tape only blocks the openings of the air vent on the face of the air vent. The tape does not block openings between the air vent and surface on which the air vent is installed. An additional drawback occurs when the tape is removed. Because the tape uses a strong adhesive, damage often occurs to the wall, ceiling, or air vent when the tape is removed.
Many audits of a building's HVAC system occur while the building is still under construction. For example, prior to the sheet rock being installed in a building, technicians will test an HVAC system for leaks and energy efficiency to allow for easy repair or adjustments prior the installation of surfaces that may hinder such repair or adjustment efforts. During subsequent construction, however, debris, dust, and dirt have the potential to enter into an HVAC system through the air vent boots and other openings in an HVAC system. Currently, construction workers attempt to prevent such debris from entering the HVAC system by taping cardboard to the HVAC openings or stuffing material into the openings to block the debris from entering. None of the current solutions serve to provide an effective seal, however, to protect the HVAC system during the final stages of construction.